1. Field of the Invention
The present invention relates to a reproduction apparatus for performance data, which performs an automatic performance (reproduction) on the basis of performance data stored in a storage medium.
2. Description of the Prior Art
In some electronic musical instruments, operation states (numbers of operated keys and switches, ON- and OFF-key timings, ON-key speeds, strengths, and the like) of a keyboard (keys), panel switches, and the like are stored, and in a reproduction mode, operations of keys and panel switches are electrically reproduced on the basis of reproduction data, thus allowing an automatic performance of a music piece. Such an electronic musical instrument is also called an automatic performance apparatus, and can reproduce and play performance data prestored in a commercially available storage medium (a floppy disk or ROM).
Some automatic performance apparatuses of this type have a function of forcibly correcting errors of performance data on the time base, e.g., offsets among notes in a chord performance. Such a function is called a just-beat function or a quantize function.
The just-beat function is realized by a computer program for rewriting time parameters (e.g., ON-key timings) of stored performance data in a conventional apparatus. This program corrects time parameters in performance data to attain a just-beat. When the corrected performance data are read out at a predetermined read speed, a just-beated reproduction performance in which errors on the time base are minimized can be made.
In the conventional apparatus, as described above, since each performance is just-beated by the computer program, just-beat processing must be performed before reproduction, and real-time processing for making a just-beat reproduction performance immediately after recording of a performance cannot be performed.
When time parameters are corrected by the just-beat function, original data cannot be restored, and it is difficult to re-correct data at a different degree (ratio) of correction, or to re-correct data just-beated in units of quarter notes to data just-beated in units of eighth notes. In order to reset just-beat parameters, original performance data must be stored without being corrected, and just-beat processing is performed for a copy of performance data, resulting in a cumbersome procedure.